Semiconductor devices for high-voltage applications commonly use vertical double-diffused metal-oxide-semiconductor field effect transistors (VDMOSFETs) or laterally diffused metal-oxide-semiconductor field effect transistors (LDMOSFETs). In order to increase the breakdown voltage of high-voltage semiconductor devices, several methods are commonly employed, such as, reducing the doping concentration of a deep well region (or known as drift region in the art), increasing the depth of the drift region, or increasing the length of an isolation structure (often referred to as a field oxide layer) underlying a gate.
However, when the breakdown voltage of a high-power semiconductor device is increased by the above-described ways, the resistance in the ON state (ON-resistance) or the size of the transistor is increased as well, which undesirably reduces the performance of the device or increases the area of a semiconductor device.
Thus, there exists a need in the art for development of a semiconductor device exhibiting increased the breakdown voltage without increasing the ON-resistance or device size.